Dental-engine hand-tool



W G SHELTON.

DENTAL ENGINE HAND TOOL.

APPLICATION HLED OCT. 6, I917.

Paten ted July 19, 1921.

' WITNESSES s mw n r w A y B WILLIAM GENTRY SHELTON, OF NEW YORK, N; Y:I

nnnrnn nnerun HAND-TOOL.

Specification of Letters Patent.

Patented July-1 9, 1921,

Application filed October 6, 1917. Serial No. 195,028.

To all 1/) 7mm it wm z concern:

Be it known that I, WILLIAM Gr. SHEL- TON, a citizen of the UnitedStates of America, residing in the borough of Manhattan, city, county,and State of New York, have invented certain new and useful Improvementsin Dental-Engine Hand-Tools, of which the following is a specification.

The object of this invention is to provide in a hand tool aself-contained dental engine and hand piece wherein the-motor is at alltimes under the control'ofthe operator by a simple movement of theposition of the hand, irrespective oftheposition of the fingers of thehand holding the hand piece. By control ofthe motor in thepresentinstance is particularly meant the starting, stopping andreversing of the motor, as oocasion' may demand. The illustrated form:of the invention shows the motorswitch controlled by a. slight rotarymovement of the hand piece upon its axis and upon the axis of rotationof the tool mounted therein when the tool is mounted in the prolongationof the axis of the hand piece. The various structural details of theinvention" are developed in their proper order in the description;

In the drawings accompanying this 1pplication, one practicableembodiment oft e invention is illustrated, inwhich drawings,

Figure l, is a top view partly in horizontal section, of one form of myimproved device.

Fig. 2, is a vertical section taken on a plan at about the line .2 2,ofFig. 1,. the crosssectional line ofFig, 1, being illustrated in thisview by the line 1-1.

Fig. 3, is an elevationof the device shown in Figs. 1 and 2, but 011 asmaller scale. In this view, the outer casing is shown broken away, forthe purpose of showing theswitch, and

Fig. 4, is a detailed view of the wiring which is found convenientinthis device;

In these drawings, Fig. 8', showsthe device full size and'Figs. 1 and 2,are'on a scale of two to one approximately.

l V hen the hand piece 5 of the instrument is grasped by the fingers ofthe operator in the usual manner of holding a dental hand piece, themotor casingG is dependent therefrom at the sideof' the hand. Thispresent invention, particularly relates to the control ofthe motivepower by means of a rotary movement of the hand piece relative to themotor casing, this" being rendered possible by the manner of connectionbe tween these two parts. The hand piece'is shown provided with an outershell, orsleeve 7-, which is mounted tubular bracket 8, fast to-theupper portion of the motor casing. The tool carrying spindle 9, islocated at-thebackend, within this tubular bracket 8. Of course, it isto be assumed that it is provided at itsforward end with a suiiicient orproper tool holding chuck. The bracket 8-; isshown-having a screwthreaded platelO, at the back end, having a screw threaded connectionwith the upper portion of the motor casing, this plate constituting aclosure for the gear housing 11. The sleeve 7, is held in its-loingitudinal'position by a ring 12, engaging a flange on the sleevean'ddrawing this up againsta screw threaded nut l3, mountedon an exteriorscrew thread on thebracket 8.

The spindle 9, is shown disposed trans versely ofthe motor shaft 14:,and the driving connection between these is preferably a reductiontransmission, there-being a worm 15- onthe armatureshaft 14 and a wormwheel 16, fast upon this spindle 9, the gears being mounted inthe-housing portion 11. According to the present showing, this is a tento one reduction.

The motor illustrated issupposed to have a shunt wound field, havingatthe lower side, or the side opposite the transmission mechanism acommutator- 17, which coacts with-brushes, one of'which is illustratedat 18, mounted parallel with the" axis of the rotation of the armatureand engaging the rear face to the commutator; A reversing switch isillustrated at 19, which-switch is shown carried by a" reciprocatory bar20, which is disposed substantially parallelwith the axis of rotation ofthe armature Compression springs 21, 22, are shown mounted upon the bar20 and locatedbetween heads 23 and 24 on the bar and the wall of themotor casing. These springs normallyhold the switch in the neutral,Orcircuitopen position.

The switch illustrated is actuated upon the rotation of sleeve'l',relative to the motor casing by means of an arm 25 fast with suchsleeve. In the presentillustration the arm-is shown provided with anintegral collar 25 embracing and secured to the sleeve; This arm isarticulated to the outer, or upperend of the bar 20. The arm 25 is shownfor rotation upon a provided with a pin 26, transversing a slot 27formed upon the motor casing.

The motor is preferably wound for operation from an ordinary electriclight fixture and is provided with an opening 28 at the lower end forthe entrance of the wires, which are indicated in the circuit diagram 4,by reference characters 29-30. One of the wires 29, is shown lead to abinding )ost 31, the other wire 30, being lead directly to one of thefingers, or switch blades 32, the other blade 33 being connected by awireEA to thebinding post 81. The tern1inals35-36 of the field 37 areshown connected to this binding post 31. The switch illustratedcomprises a block 38 of insulating material, provided on each edge withthree notches and upon respective side with diagonally disposed plates39 to. Plate 39 having a contact in Fig. 4; at the upper left handportion of the block and at the lower right hand portion and connectedby means of a wire l1, with the brush 18. The plate 10 has a contact atthe upper right hand portion and at the upper left hand portion and isconnected by a wire 42, with brush 18. In. Fig. at, the switch block isin the extreme opposite position of that shown in Fig. 2,, and theposition intermediate to these two, brings the fingers 82-33 in theintermediate notches, and out of contact with either of the plates,which is the normal, or off circuit position and the idle position ofthe engine, and which position is automatically assumed by the parts,due to theaction' of the springs 21-22, when the operatorreleaseshishold upon the sleeve 7.

The motor shaft 14: is shown provided at its opposite ends withspherical bearing surfaces 140-141. At the upper end 14:0 is shownengaging a properly prepared bearing face on the screw. cap 1 12 andthat of the lower end 1&1 engaging a properly formed socket in the endof an adjustable bearing, shown in the form of a set screw 1423, held inposition by means of a lock set screw 14:45

It is to be noted that the motor portion ofthe device is normallydependent from the dental hand piece and that the center of gravity ofthe motor portion is well below the portion of such hand piece grippedby the fingers of the operator, and that there is a rotary motion of thesleeve 7 relative to the tool spindle 9 within it and relative to themotor casing 6, and the arma ture shaft 14. Of course, it is to beunderstood that if the operator wishes the entire structure to have arigid feel in his hand, he will move the sleeve 7 and with it theactuating arm 25 to the limit of their movement, namely, until the pin26 engages the end of its guide slot 27. As a matter of fact, inmostcases, the parts will be so proportioned that upon the switchfingers 32-33, coming in the end notches of the switch block 19, the'pin 26 will be at the limit of its movement and positively stop in suchposition.

The operation of the device is substantially as follows:

The operator takes hold of the sleeve 7 of the dental hand piece in theusual, or customary manner of holding the same, and permits the motorcasing 6 to depend therefrom at the back, or side of his hand. When hewishes to establish the current, he rocks his hand, or rotates thesleeve 7, as the case may be, in'the predetermined direction for movingthe switch 19, by means of the arm 25, to establish the current forrotating the motor in its forward, or normal direction. When he desiresto stop the operation of the tool he may do so without removing it fromthe point of application, by a slight reverse rotation of the sleeve 7which will then bring the switch fingers 3233 into the intermediateposition. Sometimes in dental operations, it becomes desirable toquickly reverse the tool, as for instance, when a drill gets stuck, orwhen some portion of the apparatus becomes entangled, as for instancewith the rubber dam, in which case, the operator rotates the hand piecein the reverse direction to its full extent, causing such rotation totake place about the axis of the tool spindle 9, the switch then passesthrough the open circuit, or off current position before passing to thereverse position.

7 It is to be understood that changes in detail of construction may bemade within the scope of the claims, as occasion requires, withoutdeparting from the spirit of my invention. 7

What I claim is:

1. In a device of the character described, the combination of a dentalhandpiece adapted to carry a tool, a motor, said handpiece and motorbeing formed as a portable unit, and means controlling the operation ofsaid motor comprising a finger-actuated sleeve rotatable around saiddental handpiece.

2. In a device of the character described, the combination of a dentalhand-piece, adapted to carry a tool, a motor, said handpiece and motorbeing formed as a portable unit, means controlling the operation of saidmotor comprising a finger-actuated sleeve rotatable around said dentalhand-piece, and stops limiting the turning movement of said sleeve.

3. In a device of the character described, the combination of a dentalhand-piece, adapted to carry a tool, a motor, said handpiece and motorbeing formed as a portable unit, and means controlling the operation ofsaid motor comprising a finger-actuated sleeve rotatable around saiddental handpiece, said motor having its center 01": gravity below theaxis of said hand-piece.

4. In a device of the character described, the combination of a dentalhand-piece, adapted to carry a tool, a motor, said handpiece and motorbeing formed as a portable unit, and means controlling said motorcomprising a finger-actuated sleeve rotatable around said dentalhandpiece, said controlling means having three operative positions, tworunning and a stop position, and means normally tending to bring saidcontrolling means to its stop position.

5. In a dental engine hand tool, the combination with a dental handpiece, of a motor casing dependent from the rear end of the hand piece,a motor contained in such the operation of casing, a switch forstarting, stopping and reversing the motor, the hand piece being 20provided with a finger gripping portion having independent rotarymovement, and an operative connection between such finger grippingportion and the said switch.

In a device of the character specified 25 the combination with a toolspindle and a finger grip surrounding the same, a motor casing dependentfrom the rear end of the spindle and having its center of gravity wellbelow the axis of said spindle, a switch for lVILLIAM GENTRY SHELTON.

